senator john mccain of arizona said that's the key reason his party must now get on board. >> elections. elections. the republican party is losing the support of our hispanic citizens. and we realize that there are many issues in which we think we are in agreement with our hispanic citizens, but this is a preeminent issue with those citizens. >> ifill: mccain also said the country cannot continue to deny citizenship to children brought to the u.s. illegally. president obama has said immigration reform is at the top of his second term agenda. today his spokesman jay carney welcomed the senate agreement. >> this is a big deal. this is an important development. this is in keeping with the principles the president has been espousing for a long time, in keeping with bipartisan efforts in the past, and with the effort this president believes has to end in a law that he can sign. >> ifill: mr. obama is scheduled to unveil his own ideas on immigration reform tomorrow in las vegas. >> woodruff: so how will the politics of this new effort shake out on capitol hill? we asked two senators from the